SNOSDM7 August   2025 OPA4H838-SEP

ADVANCE INFORMATION  

  1.   1
  2. 1Features
  3. 2Applications
  4. 3Description
  5. 4Pin Configuration and Functions
  6. 5Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics: VS = ±1.25V to ±2.75V (VS = 2.5 to 5.5V)
  7. 6Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Operating Voltage
      2. 6.3.2 Input Voltage and Zero-Crossover Functionality
      3. 6.3.3 Input Differential Voltage
      4. 6.3.4 Internal Offset Correction
      5. 6.3.5 EMI Susceptibility and Input Filtering
    4. 6.4 Device Functional Modes
  8. 7Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Bidirectional Current-Sensing
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
        3. 7.2.1.3 Application Curve
      2. 7.2.2 Single Operational Amplifier Bridge Amplifier
      3. 7.2.3 Precision, Low-Noise, DAC Buffer
      4. 7.2.4 Load Cell Measurement
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
        1. 8.1.1.1 TINA-TI™ Simulation Software (Free Download)
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9Mechanical, Packaging, and Orderable Information

6.3.3 Input Differential Voltage

The typical input bias current of the OPA4H838-SEP during normal operation is approximately 30pA. In overdriven conditions, the bias current can increase significantly. The most common cause of an overdriven condition occurs when the operational amplifier is outside of the linear range of operation. When the output of the operational amplifier is driven to one of the supply rails, the feedback loop requirements cannot be satisfied and a differential input voltage develops across the input pins. This differential input voltage results in activation of parasitic diodes inside the front-end input chopping switches that combine with 10kΩ electromagnetic interference (EMI) filter resistors to create the equivalent circuit shown in Figure 6-4. Notice that the input bias current remains within specification in the linear region.

OPA4H838-SEP Equivalent Input Circuit Figure 6-4 Equivalent Input Circuit